1. Field of the Invention
The present invention relates generally to a marine engine cooling system and, more particularly, to a cooling system that is provided with a siphon inhibiting device to alleviate problems in marine engine cooling systems that can possibly result due to heated water reversing its normal flow direction when the engine is off.
2. Description of the Prior Art
Those skilled in the art of marine propulsion systems are aware of many different types of engine cooling systems. Typically, a water pump is used to draw water from the body of water in which the marine propulsion system is operated. The water is then conducted through a series of passages and into thermal communication with various heat producing components, such as the engine and its exhaust manifolds. After being used to remove heat from the heat producing components, the water is then typically combined with an exhaust stream from the engine and conducted overboard back into the body of water from which it was drawn.
U.S. Pat. No. 5,980,342, which issued to Logan et al on Nov. 9, 1999, discloses a flushing system for a marine propulsion engine. The flushing system provides a pair of check valves that are used in combination with each other. One of the check valves is attached to a hose located between the circulating pump and the thermostat housing of the engine. The other check valve is attached to a hose through which fresh water is provided. Both check valves prevent flow of water through them unless they are associated together in locking attachment. The check valve attached to the circulating pump hose of the engine directs a stream of water from the hose toward the circulating pump so that water can then flow through the circulating pump, the engine pump, the heads, the intake manifold, and the exhaust system of the engine to remove seawater residue from the internal passages and surfaces of the engine. It is not required that the engine be operated during the flushing operation.
U.S. Pat. No. 5,334,063, which issued to Inoue et al on Aug. 2, 1994, describes a cooling system for a marine propulsion engine. A number of embodiments of cooling systems for marine propulsion units are disclosed which have water cooled internal combustion engines in which the cooling jacket of the engine is at least partially positioned below the level of the water in which the water craft is operating. The described embodiments all permit draining of the engine cooling jacket when it is not being run. In some embodiments, the drain valve also controls the communication of the coolant from the body of water in which the water is operating with the engine cooling jacket. Various types of pumping arrangements are disclosed for pumping the bilge and automatic valve operation is also disclosed.
U.S. Pat. No. 6,004,175, which issued to McCoy on Dec. 21, 1999, discloses a flush valve which uses only one moving component. A ball is used to seal either a first or second inlet when the other inlet is used to cause water to flow through the valve. The valve allows fresh water to be introduced into a second inlet in order to remove residual and debris from the cooling system of the marine propulsion engine. When fresh water is introduced into a second inlet, the ball seals the first inlet and causes the fresh water to flow through the engine cooling system. When in normal use, water flows through the first inlet and seals the second inlet by causing the ball to move against a ball seat at the second inlet. Optionally, a stationary sealing device can be provided within the second inlet and a bypass channel can be provided to allow water to flow past the ball when the ball is moved against the ball seat at the first inlet. This minimal flow of water is provided to allow lubrication for the seawater pump impeller if the seawater pump is operated during the flushing operation in contradiction to recommended procedure.
U.S. Pat. No. 6,135,064, which issued to Logan et al on Oct. 24, 2000, discloses an improved drain system. The engine cooling system is provided with a manifold that is located below the lowest point of the cooling system of the engine. The manifold is connected to the cooling system of the engine, a water pump, a circulation pump, the exhaust manifolds of the engine, and a drain conduit through which all of the water can be drained from the engine.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In certain types of marine propulsion systems, water can drain and thereby create a siphon effect that draws water from other components of the cooling system. When the engine is turned off, cooling water in the outboard drive drains downward to the water line. This draining initiates a siphon effect which, in turn, draws cooling water from the heated engine in a backwards direction through the cooling circuit. The heated water from the engine then enters and remains in the fuel/water heat exchanger which, in most cases, is a coaxial heat exchanging device. The heated water in this fuel/water heat exchanger causes the liquid fuel to increase in temperature and, in certain cases, vaporize. When the operator of a marine vessel then tries to restart the engine, this partially vaporized fuel in the fuel/water heat exchanger is difficult to displace with the typical electric fuel pump that is normally used. As a result, vapor lock can be experienced.
It would therefore be significantly beneficial if a means could be provided that prevents the siphon effect from draining the water from the cooling system soon after the pump is deactivated. It would be further beneficial if the siphon inhibiting means could also allow later draining of the cooling system.
A marine cooling system made in accordance with the present invention comprises a pump, a heat producing component, and a conduit connected between the pump and the heat producing component. In a marine propulsion system, the heat producing component can be the engine itself or associated devices, such as the exhaust manifolds and the exhaust elbows.
A preferred embodiment of the present invention also comprises a valve connected in fluid communication with the conduit between the pump and the heat producing component. A ball or poppet is disposed within a cavity of the valve, with the valve having a first port and a second port. In certain embodiments of the present invention, a poppet valve can be used instead of the ball. Throughout the description of the present invention it should be understood that the use of the term xe2x80x9cballxe2x80x9d should be understood to describe the use of either a ball or a poppet valve. The first and second ports of the valve allow water to flow into and out of the valve during operation of the engine and during draining. The valve is configured to receive a stream of water into the first port from the pump and then pass the stream of water serially through the cavity and the second port to the heat producing component. The present invention further comprises a seal which is responsive to movement of the ball within the cavity and located between the first port and the cavity in order to inhibit water flow through the cavity toward the pump. The valve is positioned to dispose the first port above the second port when associated within a cooling system of a marine engine.
In a particularly preferred embodiment of the present invention, the ball is less dense than water and, as a result, floats on the water which is within the cavity of the valve. The seal is responsive to an upward movement of the ball within the cavity and, in a particularly preferred embodiment of the present invention, the seal is a ball seat which is shaped to receive the ball in sealing contact in response to movement of the ball against the ball seat. When water exists within the cavity of the valve, the water causes the ball to rise because the ball is less dense than the water. As the ball rises, it moves into contact with the ball seat and provides a seal. Also, flow of water upward within the cavity toward the first port from the second port, will also cause movement of the ball in an upward direct toward the ball seat.
In one embodiment of the present invention, the valve comprises a first portion and a second portion that are attached together to define the cavity which captivates the ball. In certain embodiments of the present invention, a ball rest is formed in the cavity proximate the second port in order to support the ball. The ball rest permits water to flow around the ball and through the second port when the ball is located on the ball rest at the bottom of the cavity.
The cooling system of the present invention can further comprise an engine having a plurality of cooling passages, with the valve being connected in fluid communication between the pump and the cooling passages. It can also comprise a thermostat housing connected in thermal communication with the valve and with the pump. Similarly, a fuel cooler and an exhaust manifold can be incorporated as part of the cooling system, with the valve being connected in fluid communication between the pump and both the fuel cooler and the exhaust manifold.
Although not a requirement in all embodiments of the present invention, it is preferable to locate the valve in the cooling system conduit between the pump and other components of the cooling system. Since the purpose of the valve of the present invention is to prevent, or at least inhibit, siphoning of water back through the pump, locating the valve closer to the pump than the heat producing components will facilitate its operation.